I purchased king sized pillowcases to replace the standard size pillowcase which comes with a Twin XL size sheet set.  These are pretty nice pillowcase, especially for a 300 thread count. They are soft, fit well  were offered in many colors.  As part of the design, there are a few fabric folds sewn in (which appear like stripes) near the open end of the pillowcase.  The space about 1 ft to the side of these stripes seems to be extremely wrinkled when removing from the dryer.  I dont know if this is from being twisted up in the washerdryer or an issue with the fabric itself but I always need to steam or press that part so they look nice and crisp with my other linens, which is really no big issue. The important thing is that they feel nice and are comfortable to sleep on (as they look like they will last a long time.)